Atsumu Miya and Sakusa Kiyoomi met at MSBY they both played for the team. Atsumu and Kiyoomi even started to grow closer

Atsumu thought he found someone he could call his friend, maybe something more, that wasn't just trying to get closer to his twin Osamu

after a year, Atsumu found out that Kiyoomi was putting up with him to get closer to Osamu

For Kiyoomi, that was the case at first, but he grew to love Atsumu (Atsumu doesn't know this)

Atsumu is silent "You alright?" Kiyoomi asked